Title: Mechanical properties, weld bead and cost universal approach for CO₂ laser welding process optimisation

Authors: K.Y. Benyounis, A.G. Olabi, M.S.J. Hashmi

Addresses: Department of Industrial Engineering, Garyounis University P.O. Box 1308, Benghazi, Libya. ' School of Mechanical and Manufacture Engineering, Material Processing Research Centre, Dublin City University, Dublin 9, Ireland. ' School of Mechanical and Manufacture Engineering, Material Processing Research Centre, Dublin City University, Dublin 9, Ireland

Abstract: The main two characteristics of Response Surface Methodology (RSM) technique are predicting and optimising the responses of interest. The objective of the current research is to set the process input parameters namely: laser power, welding speed and focused position at their optimal values to optimise the responses. In this work seven responses of interest were implemented namely: heat input, penetration, width of weld pool, width of HAZ, impact strength at room temperature, notched tensile strength and laser welding operating cost per metre of butt joints of medium carbon steel plates. Design-Expert software has been used to optimise the above-mentioned responses, using the mathematical models developed in a previous works to relate the seven responses to the laser welding input variables. In this study a technique of numerical optimisation and a graphical optimisation method have been considered. The optimisation criterion was implemented to produce laser-welded joints with the desired weld bead profiles and mechanical properties at relatively low cost by increasing the welding speed and decreasing the laser power. The results indicate that the optimal welding conditions obtained would improve the welded joints performance, increase the welding productivity and reduce the welding operating cost.

Keywords: laser welding; weld bead; mechanical properties; joint operating cost; process optimisation; RSM; response surface methodology; laser power; welding speed; carbon steel plates; mathematical modelling; welded joints; welding productivity.

DOI: 10.1504/IJCMSSE.2009.024928

International Journal of Computational Materials Science and Surface Engineering, 2009 Vol.2 No.1/2, pp.99 - 109

Published online: 04 May 2009 *

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